Precise localization of position has always been critical to neurosurgery. Knowledge of the anatomy of the brain and specific functions relegated to local areas of the brain are critical in planning any neurosurgical procedure. Recent diagnostic advances such as computerized tomographic (CT) scans, magnetic resonance imaging (MRI) scanning, positron emission tomographic (PET) scanning, and magnetoencephotographic (MEG) scanning have greatly facilitated preoperative diagnosis and surgical planning. However, the precision and accuracy of the scanning technologies have not become fully available to the neurosurgeon in the operating room. Relating specific structures and locations within the brain during surgery to preoperative scanning technologies has previously been cumbersome, if not impossible.
Stereotactic surgery, first developed 100 years ago, consists of the use of a guiding device which channels the surgery through specific parts of the brain as localized by preoperative radiographic techniques. Stereotactic surgery was not widely used prior to the advent of modern scanning technologies as the injection of air into the brain was required to localize the ventricles, fluid containing chambers within the brain. Ventriculography carried a significant complication rate and accuracy in localization was marginal.